1. Field of the Invention
This invention relates to a diesel crankcase lubricant composition. More especially, this invention relates to an anti-oxidant and corrosion inhibitor for diesel crankcase lubricant composition. More especially, this invention relates to a diesel crankcase lubricant composition which satisfies the onerous criteria of the Union Pacific Oxidation Test (UPOT) for oxidative stability and corrosion resistance.
2. Discussion of the Prior Art
Numerous diesel crankcase lubricant compositions are known. It is also known to include in such compositions anti-oxidants or corrosion inhibitors. For instance, it is known to employ a thiodiazole as a corrosion inhibitor for a diesel crankcase lubricating oil.
Unfortunately, the diesel crankcase lubricating oil compositions heretofore provided have not satisfied the criteria of the Union Pacific Oxidation Test in respect of oxidation stability and corrosion control. Such test is run by heating 300 cc of test oil to 285.degree. F. for 144 hours. The test oil contains a copper-lead steel backed test specimen and oxygen is passed through the oil at a rate of 5 liters per hour. The test requires that the weight loss of the test strip not exceed 50 mg and that the viscosity increase of the test oil be not greater than 20 percent. The weight loss of the test strip is a measure of the extent to which corrosion inhibition has been effected. The extent to which the viscosity increases is a measure of the oxidation resistance of the crankcase lubricant. Heretofore no known diesel crankcase lubricant composition has satisfied both of the criteria of the UPOT test.
It is an object of this invention, therefore, to provide a diesel crankcase lubricant composition which satisfies the onerous criteria of the Union Pacific Oxidation Test, both in respect of oxidative stability and corrosion resistance. It is a further object of this invention, therefore, to provide an anti-oxidant and corrosion inhibitor for diesel crankcase lubricant oil. It is still a further object of this invention to provide a corrosion inhibitor and/or anti-oxidant for a diesel engine oil containing composition which can be relatively inexpensively synthesized and which is readily soluble in the diesel crankcase lubricant oil.